how do you run something in Open GL mode? or does the software handle it on its own? or example, how would you get half life to use Open GL and how would you know that its using it? I’m really new at this and would appreciate any help I can get

The 3dfx Voodoo driver cd has an install in the splash screen… “minigl” just run it and it will search your drive for supported games
then select opengl in the video mode option within the game and the driver to the left should say 3dfxminidriver